The present invention relates to a mouthpiece used to equally stretch right and left side lower jaw supporting muscles thereof with a bite raising device, so as to correct one""s posture.
General bone structure of and around the upper and lower jaws is illustrated in FIGS. 17(a) and 17(b).
An occlusion of rows of teeth when the upper and lower jaws are closed is shown in FIG. 17(a). In FIG. 17(a), the skull supported on the first cervical vertebrae 25 at the top end of the spine and the upper row of teeth 22 arranged in the upper jaw 20 of a front part of the skull are shown. The lower jaw 21 having the row of teeth 23 on the lower jaw side is supported in a complex fashion by various muscles including a masseteric muscle. One naturally takes a posture where one""s head can be kept at a state in which the occlusion plane indicated by an axis X is aligned with an ideal occlusion plane (an approximately level plane). It is desirable that an axis Y perpendicular to the axis X extends along a vertical line.
It is known that the lower jaw 21 moves vertically around and further swings back and forth and side to side in a three-dimensional manner around a median atlantoaxial joint T0 between the first cervical vertebrae 25 and the second cervical vertebrae 26, and not around a point J of a temporomandibular joint 24, as shown in FIG. 17(b).
When occlusion surfaces of the teeth wear with age, for example, so that the vertical occlusal height of the opposing upper and lower rows of teeth decreases, or xe2x80x9cthe dental bite goes lowxe2x80x9d, as a whole, the upper jaw 20 tries to meet the lower jaw 21 and, as a result, the head leans forward. This causes the first cervical vertebrae 25 and the second cervical vertebrae 26 to move, forward away from their ideal positions, so that they come into a straight bar-like form. Along with the cervical vertebrae becoming out of position, the entire spinal cord is caused to hunch, leading to a possible hunchback and further causing a possible lower back problem.
On the other hand, when the vertical occlusal height is decreased at either lateral end due to a significant partial bite, improper dental care after extraction of a tooth, or excessive grinding of a carious tooth, in other words, when an axis Z perpendicular to the both axes of X and Y (a horizontally extending axis, not shown) is slanted, muscle spindles of the lower mandibular raising muscles of the lower jaw are loosened. This information is transmitted to the brain through trigeminal nerves, and gives a strong stress to the brain. In response to the information, the brain automatically signals central orders to shorten the muscle spindles. Based on the orders, the mandibular raising muscles of the lower jaw at rest are reset to be shorter and also the entire skeletal muscles of the body on the same side are reset to be shorter. These orders are issued day and night, so that the brain and muscles fatigue chronically, then causing possible deterioration of the function of the brain and body.
Then, the neck is slanted to a lower vertical occlusal height, while on the other hand, the muscles of the shoulder on the opposite side increase in tension, in order to try to prevent the slant of the neck. It is known that this muscular contraction and tension puts the vertebral artery and vertebral nerve under stress, and induce discomfort complaints, such as stiffness of shoulder, vertigo, buzzing, headache, tinnitus and visceral disturbance, and autonomic imbalance.
To improve the partial muscular stretch and tension caused by the lowering of the vertical occlusal height could result in the alleviation of disease caused by deterioration of the function of the brain and improve the athletic talents typified by one""s reflexes and dexterity, of physical capabilities typified by muscle strength and muscular balance of the entire body, and of learning ability, thinking ability and concentration power.
To this end, it is observed that a weightlifter having a horizontally deviated vertical occlusal height lifts a weight in a state in which the weightlifter""s lower vertical occlusal height end is inclined downward. In the U.S., it is compulsory for American to have bite raising mouthpieces on during the game, in order to prevent a disability caused by the muscular tension.
There has been proposed a mouthpiece used to straighten one""s back to correct the one""s posture, as disclosed by Japanese Utility Model Publication No. Sho 62-14833.
This proposed mouthpiece is designed to be fitted to either the row of teeth at the upper jaw side or the row of teeth at the lower jaw side. It comprises a first tooth row fitting piece to be fitted to the row of teeth located on one side from the median line, a second tooth row fitting piece to be fitted to the row of teeth located on the other side from the median line, and an arcuate connecting portion for connecting the pair of tooth row fitting pieces. In this mouthpiece, a plane perpendicular to a tooth axis of an opposing tooth (a shearing drag surface) is formed on a supporting surface of each of the tooth row fitting pieces by grinding for each opposing tooth.
In the mouthpiece disclosed by the publication above, it is necessary to grind and polish the shearing drag surface in a skillful manner in agreement with a teeth alignment on the non-fitting side, a moving range of intercuspal occlusal position on the lingual side and a vertical occlusal height. For example, the shearing drag surface must be adjusted for fit to each of the four back teeth at opposite ends of the rows of teeth and, besides, since the lower jaw must be moved so smoothly that one cannot feel any stress, a considerable skillfulness is required for the adjustment. It takes about 1-2 hours to do the dental treatment for each adjustment for fit. Thus, the prior art has the problems in that it fails to consider the labor of the dentist, and the medical and technical service fees which are expensive.
In light of the above-noted problems of the prior art, the present invention has been made. It is an object of the present invention to provide a mouthpiece of a simplified structure to facilitate an adjustment process for dental fit and significantly lower in price.
To accomplish the object mentioned above, a mouthpiece according to the present invention comprises an upper piece to be fitted to a row of teeth on an upper jaw side and a lower piece to be fitted to a row of teeth on a lower jaw side used in a vertically confronting relation with the upper piece, wherein one of an opposing surface of the upper piece and an opposing surface of the lower piece has at least two projections projecting toward the other piece and the other opposing surface has a supporting surface formed to support the at least two projections in abutment relation with them.
Each of the projections comprises a projecting piece formed separately from the one opposing surface and movable toward the other piece, projection height adjusting means for guiding the projecting piece toward the other piece to vary a height of the projection from the one opposing surface to a tip of the projecting piece, and projecting piece fixing means for fixing the projecting piece to the one opposing surface at a height of the projection set by the projection height adjusting means.
In the constitution mentioned above, the projection height adjusting means comprises a first sliding surface formed on the projecting piece and a second sliding surface formed on the one opposing surface to slide over the first sliding surface of the projecting piece, so as to guide the projecting piece toward the other piece.
Further, in the constitution mentioned above, the projection height adjusting means and the projecting piece fixing means comprise a first threaded portion provided on the projecting piece and a second threaded portion provided on the one opposing surface to be threadedly engaged with the first threaded portion of the projecting piece, respectively.
In any of the constitutions mentioned above, an upper tooth row fitting groove to be fitted to the row of teeth on the upper jaw side is formed on a top surface of the upper piece and a lower tooth row fitting groove to be fitted to the row of teeth on the lower jaw side is formed on a bottom surface of the lower piece, the upper piece and the lower piece being supported to the row of teeth on the upper jaw side and the row of teeth on the lower jaw side, respectively, via soft lining material filled in the upper tooth row fitting groove and the lower tooth row fitting groove.